beat box

Meaning

For example

Last year there was a guy on American Idol who was really good at beat boxing.

You do the beat box stuff and I'll bust some rhymes.

Origin: Originally "beat box" meant an electronic drum machine of the sort used to create percussive sounds in rap and hip-hop music. Musicians then began creating similar "click" and "pop" sounds with their mouths, and these musicians were called "human beat boxes". The word "beat box" then came to mean the act of creating these sounds to provide a rhythmic accompaniment to vocal artists who're reciting rhymes or rapping.

Variety

This
is typically used in American English but may be used in other varieties of English too.